Enjoying EarthSky? Subscribe.

Monstrous baby galaxies in dark matter

This nest of monstrous baby galaxies, 11.5 billion light-years away, appears to reside at the junction of gigantic filaments in a web of dark matter.

Artist’s visualization of a web of dark matter with monstrous galaxies, cradled within it. Monstrous galaxies are thought to preferentially be born at the centers of the web-like structures formed by young galaxies. Image via ALMA (ESO/NAOJ/NRAO)

Astronomers who recently used the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile said on December 5, 2015 that they’ve discovered a nest of monstrous baby galaxies, 11.5 billion light-years away. Sound intriguing? It is, and not just because the language is so colorful. What’s super interesting here is that the young galaxies appear to reside at the junction of gigantic filaments in a web of dark matter. In modern astronomical thinking, dark matter pervades our universe and is much, much more plentiful than the ordinary matter we see all around us, and of which we ourselves are made. This same dark matter acts a sort of nucleus around which the large-scale structure of our universe – with its billions upon billions of ordinary-matter galaxies – formed. And what of the monstrous galaxies? An ALMA statement said:

We are living in a relatively quiet period in the history of the universe. Ten billion years ago, long before the sun and Earth were formed, areas of the universe were inhabited by monstrous galaxies with star formation rates hundreds or thousands of times what we observe today in the Milky Way galaxy.

There aren’t any monstrous galaxies left in the modern universe, but astronomers believe that these young galaxies matured into giant elliptical galaxies which are seen in the modern universe.

So you might see that this discovery of a nest of monstrous baby galaxies, cradled in dark matter, plays into a couple of different scenarios in modern astronomy. And linking scenarios like these together is what enables astronomers to understand the universe.

On the left is an image that shows what looks like one bright monstrous galaxy. It was taken by this same team of astronomers, prior to using the ALMA telescope. In the center is a newer image, taken using ALMA. With 60 times better resolution and 10 times better sensitivity than in the earlier image, the astronomers could see not one but 3 monstrous galaxies close together. Image via ALMA (ESO/NAOJ/NRAO), NAOJ, H. Umehata (The University of Tokyo).

Specially, in this case, they are curious to know how monstrous galaxies like these formed and how they evolved in to the huge elliptical galaxies we see around us in space. ALMA said:

Current galaxy formation theories predict that these monstrous galaxies form in special environments where dark matter is concentrated. But up until now it has been difficult to determine the positions of active star forming galaxies with enough precision to actually test this prediction. Part of the problem is that monstrous star-forming galaxies are often obscured in dust, making them difficult to observe in visible light. Dusty galaxies do emit strong radio waves with submillimeter wavelengths, but radio telescopes typically have not had the resolution needed to pin-point individual galaxies.

ALMA is a radio telescope, and an extremely powerful one, with much higher resolution and sensitivity than previous telescopes. ALMA has been fully operational only since March, 2013. A team led by astronomers Hideki Umehata (you’ll find him on this ESO page), Yoichi Tamura and Kotaro Kohno used ALMA to make extensive observations of a small part of the sky, a region of space is known to astronomers as SSA22. It’s located in the direction to our constellation Aquarius the Water-Bearer.

They were able to pinpoint the locations of nine monstrous galaxies in SSA22.

The team then compared the positions of these galaxies with the location of a cluster of young galaxies 11.5 billion light-years from Earth. That galaxy cluster had been studied in visible light by Japan’s Subaru Telescope.

The shape of the cluster observed by the Subaru Telescope indicates the presence of a huge 3D web of invisible dark matter. The ALMA statement said:

This dark matter filamentary structure is thought to be a progenitor of large scale structures in the universe. One of the best known examples of large scale structure in the modern universe is the cosmic Great Wall, a gigantic filamentary structure spanning over 500 million light-years.

The filamentary structure in SSA22 could be called a proto-Great Wall.

The team found that their young monstrous galaxies seemed to be located right at the intersection of the dark matter filaments. This finding supports the model that monstrous galaxies form in areas where dark matter is concentrated.

And since modern large elliptical galaxies are simply monstrous galaxies which have mellowed with age, they too must have originated at nexuses in the large scale structure.

This is exciting stuff! It means astronomers now believe they’re learning things about the structure of our universe in ways undreamt just a few decades ago.

These astronomers said they will, of course, continue their observations.

This almost looks like an artist’s conception, but it’s not. It’s a photo taken in December 2012 of the array of ALMA antennas in in the Chilean Andes. Image via Clem & Adri Bacri-Normier (wingsforscience.com)/ESO

Bottom line: Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile said on December 5, 2015 that they’ve discovered a nest of monstrous baby galaxies, residing at the junction of gigantic filaments in a web of dark matter. They say their findings are important for understanding how monstrous galaxies like these formed and how they evolve into huge elliptical galaxies.

Deborah Byrd created the EarthSky radio series in 1991 and founded EarthSky.org in 1994. Today, she serves as Editor-in-Chief of this website. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. "Being an EarthSky editor is like hosting a big global party for cool nature-lovers," she says.